<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#greenbox {
  width: 100px;
  height: 100px;
  background: green;
  padding: 0px;
  margin: 0px;
}
#redbox {
  width: 100px;
  height: 100px;
  background: red;
  padding: 0px;
  margin: 0px;
}

td {
  padding: 0px;
}
</style>
</head>
<body style="margin:0" onload="parent.iframeLoadResolve()" contenteditable>
<table id="table_to_fill">
    <tr><td><div id="greenbox"></div></td></tr>
    <tr><td><div id="redbox"></div></td></tr>
    <tr><td><div id="greenbox"></div></td></tr>
    <tr><td><div id="redbox"></div></td></tr>
    <tr><td><div id="greenbox"></div></td></tr>
    <tr><td><div id="redbox"></div></td></tr>
    <tr><td><div id="greenbox"></div></td></tr>
    <tr><td><div id="redbox"></div></td></tr>
</table>
</body>
</html>
